Echogenic enhancement for a needle

ABSTRACT

A needle includes a surface with a plurality of first ultrasound reflecting depressions formed therein. The first depressions are distributed along at least a portion of a length of the needle separated from one another by intervening sections. Each of the first depressions is extending along a curve between first and second ends adjacent to corresponding ones of the intervening sections with troughs at which surfaces of each of the first depressions most closely approach a longitudinal axis of the needle being offset toward the first ends of each of the first depressions.

PRIORITY CLAIM

This application claims the priority to the U.S. Provisional ApplicationSer. No. 61/141,473, entitled “Echogenic Enhancement for a Needle” filedon Dec. 30, 2008. The specification of the above-identified applicationis incorporated herewith by reference.

BACKGROUND

Needle biopsies are common procedures for the diagnosis and staging ofdisease. These procedures are often done under ultrasound guidance toallow physicians performing the procedure to visualize the position ofthe needle in relation to target and surrounding tissue structures.Thus, the echogenicity of the needle (i.e., the visibility of the needleunder ultrasound) often impacts the success of the procedure. Theechogenecity may be affected by the size of the needle, a differencebetween the acoustic impedance of the needle and that of the surroundingtissue, an angle of the needle relative to the transducer, the frequencyof the ultrasound energy used and various characteristics of theprocessing algorithm.

Various techniques have been developed in an attempt to improve theechogenic properties of needles including mechanical treatments of theouter surface of the needle or echogenic coatings. However, the currentmechanical treatments involving the creation of discrete shapes repeatedalong the axis and/or about the circumference of a needle are complex toform. Other mechanical treatments include the formation ofcircumferential grooves or spirals around the needle. However, thesegrooves are tuned to only one angle and one frequency such that aslightly different spacing and/or a different frequency may have asignificant negative impact on echogenic performance. The application ofechogenic coatings increases the complexity of the devices and does notnecessarily enhance the performance of these coated devices relative tothe mechanical treatments described above. Furthermore, the echogenicproperties of these coatings may decay over time.

SUMMARY OF THE INVENTION

The present invention is directed to a needle comprising a surface witha plurality of first ultrasound reflecting depressions formed therein,the first depressions being distributed along at least a portion of alength of the needle separated from one another by intervening sections,each of the first depressions extending along a curve between first andsecond ends adjacent to corresponding ones of the intervening sectionswith troughs at which surfaces of each of the first depressions mostclosely approach a longitudinal axis of the needle being offset towardthe first ends of each of the first depressions.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a perspective view of a needle, according to an exemplaryembodiment of the present invention;

FIG. 2 shows an enlarged partial side view of a needle with depressionsalong a length of the needle, according to the exemplary embodiment ofFIG. 1;

FIG. 3 shows an enlarged partial side view of a needle with depressionsof a variety of shapes, according to a further embodiment of the presentinvention;

FIG. 4 shows an enlarged partial side view of a needle with depressionsof a variety of shapes and spaces, according to another embodiment ofthe present invention; and

FIG. 5 shows an enlarged partial side view of a needle with depressionsalong a length of the needle and a coating layer, according to a furtherembodiment of the present invention.

DETAILED DESCRIPTION

The present invention, which may be further understood with reference tothe following description and the appended drawings, relates to devicesfor conducting biopsies under ultrasound guidance. Exemplary embodimentsof the invention are directed to a pattern on an outer surface of aneedle such that the needle has enhanced ultrasound visibility, allowingthe needle to remain visible at various angles relative to thetransducer. It will be understood by those of skill in the art thatalthough the exemplary embodiments are described as a needle, the devicemay be any medical device that may be seen under ultrasound guidance. Itwill also be understood by those of skill in the art that sinceultrasound is an electromagnetic energy, the patterns described herein,which enhance visibility, may also be used with other energy sourcessuch as, for example, light.

As shown in FIG. 1, a needle 100 according to an exemplary embodiment ofthe invention comprises a longitudinal body 118 extending between adistal end 120 and a proximal end 122. An outer surface 104 of theneedle 100 includes a plurality of depressions 106 formed along at leasta portion of a length of the needle 100 to enhance the visibility of theneedle 100 under ultrasound guidance by scattering and reflecting backtoward a transducer sound waves incident thereon. The needle 100 willgenerally comprise a lumen 102 extending therethrough to an opening in adistal tip 110 at a distal end 120 of the needle 100 for collectingtarget tissue as would be understood by those skilled in the art. Asshown in FIG. 1, the tip 110 may be formed by a cut through the needle100 at an angle relative to a longitudinal axis of the longitudinal body118. so that a distal-most surface of the needle 100 extends along anangle relative to a longitudinal axis of the needle 100 with an area ofthe opening to the lumen 102 greater than a cross-sectional area of thelumen 102 within the needle 100.

As would be understood by those skilled in the art, the needle 100 maybe formed of any biocompatible material rigid enough to penetrate thetissue targeted by the procedure to which the needle 100 is directed.For example, the needle 100 may be formed of stainless steel or tungstento enhance the echogencity of the needle. As would be understood bythose skilled in the art, tungsten has an acoustic impedance greaterthan that of stainless steel increasing the difference in acousticimpedance between the needle 100 and the surrounding tissue and therebyenhancing echogenicity. It will be understood in the art, however, thatany of a variety of materials may be used to form the needle 100 so longas the material is biocompatible and provides a visible difference inechogenicity as compared to the tissue through which it will bedeployed.

The depressions 106, as shown in the enlarged side view of FIG. 2, areshaped to directly reflect sound waves received over a broad range ofangles so that the transducer may be placed in a variety of positionsrelative to the needle 100. That is, the shapes of the depressions 106are selected to present at least a part of a face thereof substantiallyperpendicular to incoming ultrasound radiation over a wide range ofincoming angles so that this radiation will be reflected back to thedevice from which it originated. Thus, a surface of the depression 106ranges from a steep portion 112 extending from a first end portionabutting a space 108 between adjacent depressions 106 nearlyperpendicular to a longitudinal axis of the needle 100 to a trough 114at which the depression 106 transitions to a shallow portion 116extending to a second end portion of the depression 106 at an angle lesssteep than that of the steep portion 112. That is, as the depth of eachof the steep portion 112 is equal to that of the shallow portion 116,the trough 114 is closer to the first end than to the second end of thedepression 106. At the first end, the surface of the steep portion 112is, therefore, close to a plane perpendicular to a longitudinal axis ofthe needle 100 sloping slightly toward a plane parallel to thelongitudinal axis. Thus, at least a portion of sound waves from atransducer positioned anywhere in the range of slightly more than 0° toclose to 90°, relative to a longitudinal axis of the needle 100 willimpact a portion of the depression 106 which is substantiallyperpendicular to a front of the wave sending the wave directly back tothe transducer. The steep portion 112 is positioned to reflect wavesback to a transducer aimed nearly parallel (close to)0° to the needle100 while the shallow portion is oriented to reflect waves back to atransducer positioned substantially perpendicular to the longitudinalaxis (close to 90°) of the needle 100 while the gradual transitionbetween these portions provides surfaces oriented to reflect back to atransducer ultrasound radiation impinging on the needle 100 at any anglebetween these extremes. It will be understood by those of skill in theart that where the transducer is positioned proximally of the distal end120 of the needle 100, the steep portion 112 may face proximally suchthat the sound waves reflect over a broad range of needle-transducerangles.

In a preferred embodiment, each depression 106 extends around an entirecircumference of the needle 100. However, it will be understood by thoseskilled in the art that the depression 106 may extend around only aportion of the circumference of the needle 100 or may be configured as aslot on the outer surface 104 of the needle 100. A space 108 which issubstantially flat along a length of the needle 100 is located betweeneach pair of adjacent depressions 106. In the embodiment shown in FIGS.1 and 2, the depressions 106 are substantially evenly spaced such thateach space 108 is equal in length. However, it will also be understoodby those of skill in the art that the length of each space 108 may varyalong the length of the needle 100. Although the needle 100 is describedas being substantially cylindrical, it will be understood by those ofskill in the art that the needle 100 may take a variety of shapes solong as it includes a plurality of depressions 106 about at least aportion of a perimeter of the outer surface 104.

It will be understood by those of skill in the art that the features ofthe needle 100, as described above may also be included in other medicaldevices that may be viewed under ultrasound guidance. For example, inanother embodiment, a sheath, which may be slidable along a portion of alength of a needle may include a pattern substantially similar to thepattern formed by the depressions 106 on the needle 100. In anotherembodiment, a stylet, which may be slidable through a lumen of a needleto prevent non-target tissue from entering the lumen may be formed witha pattern substantially similar to the pattern formed by the depressions106 on the needle 100.

A needle 200 according to another embodiment of the invention issubstantially the same as the needle 100 described above except that thedepressions 206 of the needle 200 are not all of the same shape. Forexample, the depressions 206 include a plurality of first depressions206 a each of which includes a steep portion 212 oriented to moreeffectively reflect energy back to a transducer oriented substantiallyparallel to the needle 200 from the steep portion 212 while each of aplurality of second depressions 206 b is shaped as a shallow bowl 214oriented to more effectively reflect energy to a transducer oriented ata steeper angle relative to the longitudinal axis of the needle 200 (atan angle close to 90° relative to the needle 200). In the embodiment ofthe needle 200 shown in FIG. 3, each of the first depressions 206 a islocated between a pair of second depressions 206 b are separated by aspace 208 which is substantially flat along a length of the needle 200.As described above in regard to the needle 100, the spaces 208 of theneedle 200 are substantially equal in size. However, it will beunderstood by those of skill in the art that the various depressions 206a, 206 b may be separated by spaces 208 of varying size, as shown inFIG. 4. It will also be understood by those of skill in the art that thedifferent sizes of the spaces 208 may further tune the response to thesound waves at different angles. Furthermore, those skilled in the artwill understand that more than 2 shapes of depressions 206 may beincluded in the needle 200. For example, a plurality of firstdepressions may be oriented to effectively reflect energy delivered froma probe angled between 0 and 30° relative to the longitudinal axis ofthe needle 200 while a plurality of second depressions is oriented toeffectively reflect energy delivered from a probe angled between 30 and60° relative to the longitudinal axis and a plurality of thirddepressions is oriented to effectively reflect energy delivered from aprobe angled between 60 and 90° relative to the longitudinal axis.

In a further embodiment of the present invention, as shown in FIG. 5, aneedle 300, which may be substantially similar to either of the needles100 and 200 described above, further comprises a coating layer 316covering a plurality of depressions 306. Although FIG. 5 shows theneedle 300 including depressions 306 of a single shape as in the needle100, it will be understood by those of skill in the art that the coatinglayer 316 may be included on any of the needle embodiments describedabove with any variety of depression shapes and spacings. The coatinglayer 316 may be formed of a material having an acoustic impedancesimilar to that of the body tissue within which the needle 300 is to bedeployed, but with a lower speed of sound transmission therethrough.This difference in the speed of sound transmission through the tissueand the coating layer 316 refracts the sound waves toward the needle300, steepening their angle of impact and improving the amount ofacoustic energy reflected back to the transducer. An example of acoating layer that may be used is PTFE, which has a lower speed ofsound, resulting in the refracted sound waves. A depth of the coating316 may also be varied to optimize constructive interference andminimize destructive interference between incoming sound waves andreflected sound waves leaving the surface 318 of the coating 316.

The embodiments of the present invention, as described above, may beeasily manufactured using a simple tool. For example, the depressions106 may be formed in the needle 100 using a tool with a protrusion aprofile of which matches a desired shape of the depression 106. The toolmay be rotated about a circumference, or a part of a circumference, ofthe needle 100 with the protrusion contacting the outer surface 104 toform the depressions 106 in the longitudinal body 118 the needle 100 aswould be understood by those skilled in the art. Alternatively, insteadof rotating the tool about the needle 100, the needle 100 may be rotatedabout a longitudinal axis of the needle while the tool remainsstationary such that the protrusion contacts the outer surface 104 ofthe needle 100. The plurality of depressions 106 may be formed by simplymoving the tool along the longitudinal axis of the needle 100 or bymoving the needle 100 along the longitudinal axis, by a desired distanceof the space 108, and rotating the tool or the needle 100 as describedabove. This may be repeated until a desired number of depressions 106have been formed. Alternatively, a tool may include multiple protrusionsto form the desired number of depressions 106 in one operation or in areduced number of operations. For example, a tool to form a needle suchas the needle 200 may include a first protrusion having a shapecorresponding to the desired shape of the first depressions 206 a whilea second protrusion has a shape corresponding to a desired shape of thesecond depressions 206 b, etc.

Alternatively, patterns formed by the depressions 106, 206, 306 may beapplied to the needles 100, 200, 300, respectively, in the form of ringsor other similar elements applied around at least a portion of the outersurfaces of the needles 100, 200 and 300. In another embodiment, a pressmay be used to stamp the needles with the depressions 106, 206, 306 toform the desired patterns on the needles 100, 200 and 300. In anotherembodiment, the depressions 106, 206 may be formed by lasermicro-machining or by using an EDM process. However, it will beunderstood by those of skill in the art that any of a variety of methodsmay be used for forming any of the depressions 106, 206, 306 in theneedles 100, 200, 300. As would be understood by those skilled in theart, once the depressions 306 have been formed by any of theabove-described methods, the needle 300 may be coated with a desiredthickness of the selected material to form the coating 306 using anyknown technique.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the structure andmethodology of the present invention, without departing from the spiritor scope of the invention. Thus, it is intended that the presentinvention cover the modifications and variations of this inventionprovided that they come within the scope of the appended claims andtheir equivalents.

What is claimed is:
 1. A needle, comprising: a surface with a pluralityof first ultrasound reflecting depressions formed therein, the firstdepressions being distributed along at least a portion of a length ofthe needle separated from one another by intervening sections, each ofthe first depressions extending along a longitudinal axis of the needleand including a curve having a longitudinally varying curvature betweena steep slope at a first end and a shallow slope at a second end, ateach of the first ends the steep slope gradually transitions to extendsubstantially perpendicular to the longitudinal axis of the needle, andthe first and second ends of each of the first depressions are adjacentto corresponding ones of the intervening sections with troughs at whichsurfaces of each of the first depressions most closely approach thelongitudinal axis of the needle being offset toward the first ends ofeach of the first depressions.
 2. The needle of claim 1, wherein theneedle includes a lumen extending therethrough.
 3. The needle of claim2, further comprising a tip located at a distal end of the needle, thetip being formed angled relative to the longitudinal axis of the needleand adapted to receive therein bodily tissue penetrated by the needle.4. The needle of claim 1, wherein each of the first depressions extendsaround an entire circumference of the needle.
 5. The needle of claim 1,wherein each of the first depressions extends around only a portion of acircumference of the needle.
 6. The needle of claim 1, wherein the firstend of each of the first depressions is at a distal end thereof.
 7. Theneedle of claim 1, further comprising a plurality of second ultrasoundreflecting depressions distributed along at least a further portion ofthe length of the needle separated from one another by the interveningsections, each of the second depressions extending along a curve betweenfirst and second ends adjacent to corresponding ones of the interveningsections with troughs at which surfaces of each of the seconddepressions most closely approach the longitudinal axis of the needlebeing offset toward the second ends of each of the second depressions.8. The needle of claim 7, wherein the second end of each of the seconddepressions is at a proximal end thereof.
 9. The needle of claim 7,wherein lengths of the intervening sections vary along the needle. 10.The needle of claim 1, wherein the intervening sections aresubstantially equal in length.
 11. The needle of claim 1, furthercomprising a plurality of third ultrasound reflecting depressionsdistributed along at least a further portion of the length of the needleseparated from one another by the intervening sections, each of thethird depressions extending along a curve between first and second endsadjacent to corresponding ones of the intervening sections with troughsat which surfaces of each of the third depressions most closely approachthe longitudinal axis of the needle being substantially centered betweenthe first and second ends of each of the third depressions.
 12. Theneedle of claim 11, wherein the first and third depressions alternatealong the length of the needle.
 13. The needle of claim 1, wherein alongitudinal body of the needle is formed of one of stainless steel andtungsten.
 14. The needle of claim 1, further comprising a coatingcovering at least a portion of the needle, a material of the coatinglayer having an acoustic impedance selected to substantially match anacoustic impedance of bodily tissue within which the needle is to beused.
 15. The needle of claim 14, wherein a speed of sound through thematerial of the coating layer is substantially less than that throughthe bodily tissue within which the needle is to be used.
 16. A medicaldevice, comprising: a surface with a plurality of first ultrasoundreflecting depressions formed therein, the first depressions beingdistributed along at least a portion of a length of the device andseparated from one another by intervening sections, each of the firstdepressions extending along a longitudinal axis of the device andincluding a curve having a longitudinally varying curvature between asteep slope at a first end and a shallow slope at a second end, at eachof the first ends the steep slope gradually transitions to extendsubstantially perpendicular to the longitudinal axis of the device, andthe first and second ends of each of the first depressions are adjacentto corresponding ones of the intervening sections with troughs at whichsurfaces of each of the first depressions most closely approach thelongitudinal axis of the device being offset toward the first ends ofeach of the first depressions.